Certain benzimidazole as rodenticides

ABSTRACT

Benzimidazole compounds of the formula   WHEREIN R is alkyl of one to 12 carbon atoms and R1, R2, R3 and R4 are the same or different and are selected from the group consisting of hydrogen and halogen, not more than three of the groups R1-R4 being hydrogen are useful as rodenticides.

United States Patent [451 July 11, 1972 Saggers [54] CERTAIN BENZIMIDAZOLE AS RODENTICIDES [72] Inventor: David Thomas Saggers, Saffron Walden,

England [73] Assignee: Fisons Limited, Felixstowe, Suffolk, En-

gland [22] Filed: Nov. 28, 1969 211 Appl. No.: 880,938

[30] Foreign Application Priority Data Dec. 3, 1968 Great Britain ..57,43 H68 [52] U.S. Cl ..424/273, 424/ l 7, 424/84 [51] Int. Cl. .;....A0ln 9/22 [58] Field of Search ..424/l7, 273, 84; 260/3092 [56] References Cited UNITED STATES PATENTS 3,531,495 9/1970 Burton et al ..424/273 Primary Examiner-Jerome D. Goldberg Assistant Examiner-Vincent D. Turner Attorney-Wenderoth, Lind & Ponack [5 7] ABSTRACT Benzimidazole compounds of the formula C R C CN CC F; 11 N wherein R is alkyl of one to 12 carbon atoms and R, R R and R" are the same or different and are selected from the group consisting of hydrogen and halogen, not more than three of the groups R R being hydrogen are useful as rodenticides.

13 Claims, No Drawings CERTAIN BENZIMIDAZOLE AS RODENTICIDES The present invention relates to an improved process and composition for the destruction of rodents, particularly rats and mice and allied pests.

The serious depredations resulting from rat infestation are well known; quite apart from the actual consumption and spoilage of food in store and in the fields, rats represent a serious health hazard due to the diseases for which they are carriers. The destruction of rats is therefore a serious public health requirement, and any process for the destruction of rats, mice and other rodents results in improvement of storage facilities and farm areas, thus rendered free from rat infestation.

Many compounds exist which are toxic to rats and mice; the problem which has to be overcome is the provision of a toxic compound which will be consumed by the rodent. Thus rodenticides are normally formulated in a food bait; many toxic substances are repellant to rodents, so that in normal circumstances the rodent is disinclined to consume the poisoned bait. The toxic substance therefore in addition to being toxic to the rodent, also requires to be acceptable by smell and taste, or at least non-pepellant to the rodent, so that the poisoned bait is consumed by the rodent.

It has now been found that the substituted trifluoromethyl benzimidazoles hereinafter referred to, in addition to being highly toxic to rodents, particularly rats and mice, are also palatable to rodents.

Accordingly, the present invention is for a rodenticidal composition which contains an amount effectively toxic to rodents of a substituted benzimidazole of the formula:

wherein R is hydrogen or an alkyl group (for example of 1-12 carbon atoms such as methyl, ethyl, propyl, butyl, decyl or dodecyl), and wherein R, R R and R are the same or different and are selected from hydrogen, halogen (for example chloro, bromo, fluoro or iodo) and pseudo halogen (for example cyano), not more than three of the groups RR being hydrogen, or salts or functional derivatives thereof, in a solid or liquid carrier consumable by the rodent. Desirably not more than one of the groups R'-R is hydrogen. According to a preferred embodiment of the invention R is an alkyl group of one to three carbon atoms.

Compounds where R is hydrogen form salts such as metal and amine salts. These may be used in form of water soluble salts such as the alkali metal salts, but it is usually preferred to use an insoluble salt, such as the barium or calcium salt.

The present invention is also for a process of freeing buildings or areas from rodents, particularly rats and mice, which comprises introducing into the buildings or areas a rodenticidal composition as identified above.

The activity of the substituted benzimidazoles increases with decrease in particle size. Thus according to a preferred embodiment of the invention the substituted benzimidazole is micronized, for example, with sugar, china clay, or talc, and the resulting micronized powder used in the rodenticidal compositions. According to one embodiment of the invention the substituted benzimidazole is of a particle size of about 1 to 20 microns and preferably about 5 to microns. It is usually necessary to grind or micronize the substituted benzimidazole in admixture with a solid diluent (for example comprising 10-20 percent by weight of the substituted benzimidazole). Since the heat of grinding may cause fusion of the substituted benzimidazole where this is micronized alone.

The rodenticidal composition is suitably in the form of a palatable composition containing the substituted benzimidazole. The rodenticidal composition suitably contains 0.025 to 5 percent, and preferably 0.1 to 2 percent, by weight of the substituted benzimidazole.

The rodenticidal composition suitably contains a bait" for the rodent in the form of a solid substance edible by the rodent; such substances include oatmeal, cereals, cereal products, sugar, molasses, oil cake, lucerne flour, dried fungi, vegetables, vegetable products, bran, biscuits and the like. In addition the composition may also contain inert carriers such as talc, chalk and the like. In such cases the composition is suitably formulated as pellets or granules, which can be scattered in buildings or other rat infested areas.

The rodent will normally make several feeds of the rodenticidal composition, and the effect of the substituted benzimidazole poison is cummulative. By reason of the low concentration of the substituted benzimidazole in such compositions, these are not dangerous to children or domestic animals.

Although it is preferred to use the substituted benzimidazole in the form of solid palatable composition, this may also be presented in a liquid composition, for example in a syrup, or may be introduced into the drinking water used by the rats; such liquid compositions may, if desired, include a wetting agent.

Other types of composition include tracking powders," comprising a finely divided powder for example talc, containing the substituted benzimidazole. The tracking powder is dusted on the floor over which the rodents walk, and the rodents consume the composition when they clean themselves. Such compositions suitably contain 0.l to 5 percent by weight of the substituted benzimidazole. These compositions may also contain a surface active agent so as to prevent agglomeration of the powder, and may also contain dyestuffs, to make the dust less conspicuous on floors.

The substituted benzimidazole of the formula indicated above where R is hydrogen are the most toxic to rodents; however, the compounds where R is alkyl, although less toxic are more palatable, so that the rodents quickly consume a toxic dose. Furthermore, the slow onset of toxic symptoms ensures that the rodents consume a toxic dose before side effects reduce their desire for food. Palatability is further improved by the use of insoluble salts, and/or by presenting the benzimidazole in capsule or micro-encapsulated form, for example in gelatin. Preferred compounds which may be mentioned include, 4, 5, 6, 7-tetrachloro-Z-trifluoromethyl benzimidazole, l-methyl-4,5 ,6,7-tetrachloro-2- trifluoromethyl benzimidazole, l-normalpropyl-4,7-dibromo- 5,6-dichloro-2-trifluoromethyl benzimidazole, l-normalpropyl-6-bromo-4,5,7-trichloro-2-trifluoromethylbenzimidazole, l-normalpropyl-4,6-dibromo-5,7-dichloro2- trifluoromethyl benzimidazole, l-methyl-4-bromo-5,6,7- trichloro-Z-trifluoromethyl benzimidazole and l-methyl-5- cyano-4,6,7-trichloro-2-trifluoromethyl benzimidazole.

A specially preferred compound, particularly for a mice poison is l-normalpropyl-4,5,6,7-tetrachloro-2- trifluoromethyl benzimidazole. Another specially preferred compound, particularly for a rat poison is l-methyl-4-bromo- 5,6,7-trichloro-Z-trifluoromethyl benzimidazole.

If desired the rodenticide composition according to the present invention may contain in addition to the substituted benzimidazole another rodenticide such as rodenticide of the anticoagulant type for example warfarin or other types of rodenticides for example norbormide or alphachloralose.

The following examples are given to illustrate the present invention.

EXAMPLE 1 Oatmeal pellets were prepared containing 1 percent by weight of 4,5 ,6,7-tetrachloro-2-trifluoromethyl benzimidazole. These pellets were fed to rats in the absence of other food. Mortality over a period of hours is shown below:

Hours of exposure to bait rat mortality I Compound ll l-,,propyl-4,7-dibromo-5,6-dichloro-2- fig trifluoro-methyl benzimidazole 78 00 Compound lll l,,propyl-6-bromo-4,5.7-trichloro-2- trifluoro-methyl benzimidazole Compound IV 1-,,propyl-4,6-dibromo-5,7-dichloro-2- trifluoro-methyl benzimidazole EXAMPLE 2 Compound V l-methyl-4-bromo-5,6,7-trichloro-2- trifluoro-methyl benzimidazole Oatmeal pellets were prepared containing 2 percent by Co|umn A=Tomhreated f d eatenin gms weight of the substituted benzimidazole indicated below. Co|umnB=Tota1a|temative f d eatenin gms (1111111l:1l.lv1-|11-1'1-1-nl.1|11111s1-11111|l11ll1.y,1l:1ys

of funding l1'1'1'1'11l (11111111111111l 11.i. l .2 3 4 I3 1i 7 X 11 111 11 A It 11. 25 11 11 75 117 1 11111 11111 11111 11111 11111 11111 11:1 1111 1.. 11.125 11 11 1 511 R1 11-1 11 1 11 1 11-1 111 11111 111 1:7 11.1111: 11 11 11 11 1. 12 511 $1 11 111 s"? 111s 1:11 II 7 1 11.1 11 11 511 111 117 s7 17 11111 11111 11111 11111 111: 11;: 1 11.1112 11 12 12 .11 31 .1s as as as as 511 121 1111. In 7 7 1 11.1g5 11 113 11 111 111 11-1 111 11111 11111 11111 111 .55 r 1 11.0112 11 12 11 111 111 1 1 111 111 111 11-1 111 1111 .1 IV 7 w V V 7 g 1 0.125 11 12 511 117 a? 21 1 14 1 1 11-1 1 11 1 11 111 1113 '1 0.0112 11 11 25 50 75 15 15 .5 75 .5 .5 1111 111 v a *2; 9g :5; 99 P 813 1 151 111 .11 b. 31

These pellets were made available to rats together with equal EXAMPLE 5 proportions of unadulterated food. Mortality of the rats over a period of hours is shown below: A trackmg powder was prepared by m1cron1z1ng 20 parts of l-normalpropyl-4,5,6,7-tetrachloro-2-trifluoromethyl Ra Momliy benzimidazole and 80 parts of talc to an average particle size Compound Hours of exposure to bait of5 microns, and diluting this with talc of average part1cle size 1 24 48 72 96 5 microns to give a powder containing 1 percent of the l-normalpropyl-4,5,6,7-tetrachloro-2-trifluoromethyl 1-methyl-4.5,6,7-tetrachloro-2- 0 0 90 100 100 benzimidazole. "muommehylbenzimidamle This powder was dusted over runs frequented by mice;

within 3 days all traces of mice had been cleared. l-n-propyl-4,5,6,7-tetrachloro- 0 20 100 100 100 5 lclaimi z-"ifluowmclhyl benlimidamle l. A method of using a benzimidazole compound of the formula e EXAMPLE 3 Oatmeal pellets were prepared containing 0.5, 0.25, and F3 0.0125 percent by weight (shown in the column headed a a.i." below) of 4-bromo-l-methyl-5,6,7-trichloro-2- R trifluoromethyl benzimidazole. These pellets were made 0 R available to rats together with equal proportions of the unadulterated food continuously for 10 days. The rats were I caged individually and each day the mortality of the rats was wherem R alkyl of 142 carbon atoms and R21 and R4 recorded and the treated and untreated food was weighed and are the Same different and are Selected from the group replenished. Ten rats were used for each dosage rate. The Sistihg of hydrogen and halogehi not more than three of the results are summarized in the following table. The total g p being hydrogen, as a rodemicide which treated food eaten (in grams) is given in column A below, and prises applying said compound to a locus infested with rodents the total alternative food eaten (in grams) is given in column B whereby said rodents consume a rodenticidally effective below. amount of said compound.

2. A method according to claim 1 wherein the compound is Cumulative percent rat mortality, days of applied in the form of a rodenticidal composition comprising a percent M'dmg rodenticidally effective amount of the compound and a com- 111. 1 2 3 1 5 1 7 s 11 10 A B patible carrier therefor. M 10 30 100 100 100 100 100 100 100 100 65 1 3. A method as in claim 2 wherein the composition is in the g -;-g 8 8 g 28 2g 3g 3g 3g 33 $8 form of a solid substance edible by the rodents or in the form of a finely d1v1ded powder.

4. A method as in claim 2 wherein the composition contains EXAMPLE 4 an additional rodenticidally effective compound as an active ingredient.

Oatmeal pellets were prepared containing the 5. A method as in claim 2 wherein the composition contains benzimidazole compounds listed in the first column of the from 0.025 to 5 percent by weight of the benzimidazole comtable below at rates in percent by weight indicated in the pound. second column (headed as a.i."). The pellets were made 6. A method according to claim 1 wherein the available to mice together with equal amounts of untreated benzimidazole compound is present in a form selected from food continuously for 14 days. Each day the treated and unthe group consisting of capsulated and micro-encapsulated treated pellets were weighed and replenished and the mortaliforms. ty of the mice recorded. Sixteen mice were used for ea h 7. A method as in claim 1 wherein the benzimidazole comdosage rate, caged in groups of four. The results are sump n n h r inRis alkylOfl-3 arbon atoms. marized in the following table, 8. A method as in claim 1 wherein the benzimidazole com- Compound I l-,,propyl-4,5,6,7-tetrachloro-2-trifluoropound is one in which not more than one of the groups RR methyl benzimidazole is hydrogen.

6 benzimidazole compound is l-methyl-4-bromo-5,6,7- trichloro-2-trifluoromethyl benzimidazole.

13. A method according to claim 7 wherein the benzimidazole compound is l-normal-propyl-4,5,6,7- tetrachloro-2-tri-fiuoromethyl benzimidazole. 

2. A method according to claim 1 wherein the compound is applied in the form of a rodenticidal composition comprising a rodenticidally effective amount of the compound and a compatible carrier therefor.
 3. A method as in claim 2 wherein the composition is in the form of a solid substance edible by the rodents or in the form of a finely divided powder.
 4. A method as in claim 2 wherein the composition contains an additional rodenticidally effective compound as an active ingredient.
 5. A method as in claim 2 wherein the composition contains from 0.025 to 5 percent by weight of the benzimidazole compound.
 6. A method according to claim 1 wherein the benzimidazole compound is present in a form selected from the group consisting of capsulated and micro-encapsulated forms.
 7. A method as in claim 1 wherein the benzimidazole compound is one wherein R is alkyl of 1-3 carbon atoms.
 8. A method as in claim 1 wherein the benzimidazole compound is one in which not more than one of the groups R1-R4 is hydrogen.
 9. A method as in claim 1 wherein the benzimidazole compound is micronized.
 10. A method as in claim 9 wherein the compound particle size is in the range of 1 to 20 microns.
 11. A method as in claim 10 wherein the compound particle size is in the range of 5 to 10 microns.
 12. A method according to claim 7 wherein the benzimidazole compound is 1-methyl-4-bromo-5,6,7-trichloro-2-trifluoromethyl benzimidazole.
 13. A method according to claim 7 wherein the benzimidazole compound is 1-normal-propyl-4,5,6,7-tetrachloro-2-tri-fluoromethyl benzimidazole. 